Pharmacology is the branch of science concerned with the study of drugs, their actions on living systems, mechanisms of action, uses in treatment, and adverse effects. Pharmacology serves as the critical link between basic sciences (chemistry, physiology, biochemistry) and clinical medicine, guiding rational therapeutics.
Core Divisions of Pharmacology
Division
Description
Pharmacodynamics
Study of what drugs do to the body—mechanisms, sites, and effects
Pharmacokinetics
Study of what the body does to drugs—absorption, distribution, metabolism, excretion (ADME)
Pharmacotherapeutics
Clinical use of drugs for prevention, diagnosis, and treatment
Toxicology
Study of poisonous effects of drugs and other chemicals
Pharmacogenomics/genetics
Influence of genetic makeup on drug response and metabolism
Pharmacy/Pharmaceutics
Drug formulation, compounding, stability, and delivery
Key Terms and Concepts
Drug: Any chemical agent that affects biological systems; includes medications, toxins, and endogenous compounds when given exogenously.
Receptor: Specific cellular protein or structure to which a drug binds to initiate its action.
Agonist vs Antagonist: Agonists activate receptors to produce effects. Antagonists bind and block them, preventing activity.
Dose-response relationship: The relationship between the dose of a drug and the magnitude of effect.
Therapeutic index: Ratio between toxic and therapeutic doses; measure of safety.
Pharmacodynamics: Mechanisms and Effects
Receptor Binding: Most drugs act via receptors (membrane-bound, intracellular, enzyme, ion channel, nuclear). Effects may be stimulatory, inhibitory, or modulatory.
Efficacy and Potency: Efficacy is the maximum effect a drug can produce. Potency is the amount (dose/concentration) required for effect.
Types of Effects:
Therapeutic effect: Desired clinical outcome.
Side effect: Unwanted, often predictable but non-dangerous effect.
Trevor AJ, Katzung BG, Kruidering-Hall M, et al. Katzung & Trevor’s Pharmacology: Examination & Board Review. 13th ed; 2021.
Rang HP, Dale MM, Ritter JM, et al. Rang & Dale’s Pharmacology. 9th ed. Elsevier; 2019.
Reference
Mentor, Pharmacology. Pharmacology: An Introduction. Pharmacology Mentor. Available from: https://pharmacologymentor.com/pharmacology-an-introduction/. Accessed on October 7, 2025 at 15:30.
Medical Disclaimer
The medical information on this post is for general educational purposes only and is provided by Pharmacology Mentor. While we strive to keep content current and accurate, Pharmacology Mentor makes no representations or warranties, express or implied, regarding the completeness, accuracy, reliability, suitability, or availability of the post, the website, or any information, products, services, or related graphics for any purpose. This content is not a substitute for professional medical advice, diagnosis, or treatment; always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition and never disregard or delay seeking professional advice because of something you have read here. Reliance on any information provided is solely at your own risk.